Many tachyarrhythmias are mediated at least in part by the autonomic nervous system (ANS) of a subject, or patient. Accordingly, targeting the ANS for treating cardiac arrhythmias is of increasing interest. For example, application of spinal cord stimulation (SCS) to cardiac diseases is of particular interest. In fact, it has been demonstrated that thoracic SCS may alter electrophysiologic properties of both the left and right atriums, and may slow the onset of atrial fibrillation (AF). Further, SCS has proven efficacy for treating angina pectoritis.
Subjects for which SCS is utilized to treat cardiac symptoms typically have an implantable cardioverter-defibrillator (ICD) or cardiac resynchronization therapy pacemaker with defibrillation therapy (CRT-D) already implanted at the time of SCS system implantation. Accordingly, current therapy systems require both an ICD-type device and a separate neuromodulation system to treat heart failure (HF) and/or arrhythmia using SCS methods. However, this may be relatively expensive, as both ICD systems and SCS systems are relatively expensive. Further, while ICDs are typically utilized for life-saving therapy, SCS systems are generally used for palliative therapy/symptom relief.
Even if SCS is a viable treatment option for HF, it is possible that the resultant reduction of tachyarrhythmias will not be complete, and that patients using SCS for anti-tachycardia indications would still require some form of redundant, or “backup” protection in the event arrhythmia occurs. Further, even if neurostimulation is shown to reduce HF symptom severity significantly, many recipients of the SCS therapy would still be candidates for an ICD.